Physics Review Flashcards
(244 cards)
1
Q
What’s the maximum number of shades of gray in an 8 bit digital scan convertor?
A
256
2
Q
What type of resolution is most affected by the mechanical focus on a linear array transducer?
A
Elevational resolution
3
Q
what three colors a re used on a color monitor to produce the range of available colors\
A
RGB
4
Q
Which phenomenon is associated with a pattern produced by a sound beam after passing through a small aperture?
A
Diffraction
5
Q
Reolution When your patient asks you how much longer the ultrasound test, his voice his in the audible frequency range. Which of the following frequencies is in the audible frequency range?
A
10 kHz
6
Q
What information is present in the A-mode display?
A
Amplitude and reflector distance
7
Q
Which of the following is NOT a function of the receiver?
A
Not sure Dynamic Aperture???
8
Q
What term refers to regions of decreased particle density in a sound beam?
A
Attenuation??
9
Q
Wave length is measured in:
A
Millimeters
10
Q
Terms used to describe the strength of the sound beam?
A
Intensity and amplitude
11
Q
What 2D limitation is addressed by 3D ultrasound imaging?
A
3D provides visibility of the coronal plane
12
Q
Which transducer would provide the longest near-zone length?
A
10 MHz 6mm diameter aperture (hint is biggest diameter).
13
Q
An interaction of echoes that leads to reinforcement rather than to partial or total cancellation is known as:
A
Constructive interference
14
Q
You are scanning an interface with a high acoustic impedance mismatch. How will this be displayed on the B-mode image?
A
A bright dot
15
Q
Sonographic images are usually compressed before sending to PACS in order to:
A
Reduce the time to transmit the image
16
Q
You are manipulating a volume dataset that was previously obtained on your patient. What is the maximum number of imaging planes that can be obtained from this dataset?
A
There is no limit.
17
Q
With a standard one-dimensional linear array transducer, what type of resolution is affected most by electronic focusing and dynamic aperture?
A
Lateral resolution
18
Q
When you switch from a 2.5 MHz to a 5 MHz transducer, the sound wavelength:
A
Halves
19
Q
What artifact is being described in the previous question?
A
Grading lobes??
20
Q
These B-mode images of a carotid artery show a graphic overlay indicting the number of lines of sight used to acquire each frame of information. No other system parameter was adjusted., Which statement below is true comparing image A to image B?
A
Image A has better lateral resolution than image B.
21
Q
Where are images stored in the ultrasound system?
A
The scan converter
22
Q
The salt and pepper appearance you observe in this ultrasound image is a result of:
A
Acoustic speckle
23
Q
What interaction of ultrasound and tissue is primarily responsible for imaging the internal structure of organs
A
Scattering
24
Q
What is the main advantage of using of a 1.5D or multirow array transducer?
A
Narrow slice thickness over large part of the scanned volume.
25
The spatial resolution of the scan converter is determined by
Number of pixels in the scan converter matrix
26
10 to the -3 equals
1/1,000
27
When you select compound imaging, which artifact is less likely to be observed?
Refraction, Shadowing, Enhancement, Acoustic speckle
| All of the above
28
What system component is responsible for transmit focusing?
Beam former
29
Which transducer would have a lower line density in the far field compared to the near field?
Curved, tightly curved and phased array (B,C,D)
30
A method used to improve frame rates with multizone electronic focusing is termed:
Parallel processing
31
Increasing the number of acoustic scan lines in one frame improves which of the following?
lateral resolution
32
What is another name for the hyperechoic artifact distal to a fluid structure
Enhancement
33
The elapsed time between the transmitted pulse and the detected echo is 26 microsecond. How far is the interface from the transducer?
2 cm??
34
When increasing the number of transmit focal zones to improve spatial resolution, the tradeoff is
Lateral resolution vs temporal resolution
35
Which of the following interactions of sound and tissue decreases the intensity of the transmitted beam?
Absorption, Reflection, Scattering, Conversion of sound to heat (All of the above)
36
What artifact might you see with an array transducer due to energy that propagates from the transducer in a direction different from the primary beam?
Grating lobe
37
What sound-tissue interaction is necessary to form an ultrasound image?
Reflection
38
Which factor LEAST influences axial resolution
Beam width
39
You have expNDED THe IMAGE SECTOR WIDTH TO IMPROVE VISUALIZATION OF A LARGE MASS. wHAT CAN YOU DO TO maintain the same temporal resolution you had before your adjustment?
Decrease the number of focal zones.
40
Increasing the dynamic range setting affects the ultrasound image by:
Decreasing image contrast
41
The dark area indicated by the arrow in this image is primarily due to
Increased attenuation
42
The range equation describes the relationship between
Round-trip pulse travel time and distance to the reflector
43
Which is an assumption of sonographic imaging that determines how detected echoes are mapped in the image?
Echoes originate from the most recently transmitted pulse.
44
In the scan converter, interpolation is performed to
Fill in the empty pixels that occur between acoustic scan lines
45
During a sonographic exam, you adjusted the following controls. Which one was most likely to have affected the frame rate?
TGC??
46
What best describes the difference between the frequencies for Doppler and for B-mode imaging with a given transducer?
The frequency for Doppler is usually lower than B-mode imaging.
47
What can you do to enhance the visibility of a specular reflector?
Scan with perpendicular incidence.
48
Which technology would be most helpful to obtain accurate anatomic volume measurements?
3D imaging
49
What control could you adjust to improve the signal-to- noise ratio on the image?
Frame averaging
50
Which echo amplitude in the following illustration would produce the brightest dot on a B-mode display?
E The highest amplitude
51
Which control would you adjust to alter the dynamic range of the displayed echoes?
Compression
52
What term describes the ability of an imaging device to separate closely spaced objects?
Resolution
53
What type of transducer will improve the volume averaging demonstrated in this image?
1.5D or multi-row array
54
Axial resolution is improved with
Increased bandwidth, Shorter pulse length and shorter wavelength (E-All of the Above)
55
Which of the following will NOT improve axial resolution?
Increased focusing
56
Resolution of two structures at different depths along the path of the sound beam is termed
Axial resolution
57
What control should you adjust to better compensate for the attenuation of sound as it propagates through tissue.?
TGC
58
You are observing a sonographic artifact based on the interference patterns of scattered echoes. What artifact are you imaging?
Acoustic speckle
59
The speed of sound is defined as the
Speed at which the sound wave propagates through the medium.
60
Which statement is most accurate regarding resolution with a standard one-dimensional linear array transducer?
Elevational resolution. It is the worst measure of resolution with type of transducer.
61
What determines the speed of sound
Medium through which sound wave passes
62
Which of the following is most likely to decrease beam intensity?
Increasing a beam area
63
While performing an ultrasound exam, you decide to adjust the system settings to improve the image. Which of the following is not user adjustable?
Echo arrival time
64
What system function is limited by the speech of sound in tissue?
PRP
65
What type of imaging results in selective reception of frequencies that are 2 times that of the transmitted frequency?
Tissue harmonic imaging
66
What best describes the method used to created the triangular-shaped image format in the image below?
Electronic steering with most elements fired for echo pulse-echo sequence. Small time differences steer the beam.
67
How can you optimize your system to demonstrate a shadow distal to the calcification?
Increase the transducer frequency
68
The propagation speed for sound is lowest in which of the following biological tissues?
Fat. Bone has a high propagation speed which will cause attenuation.
69
If you wish to use an array transducer that allows you to control transmit focal depth. What type would you select.
All of the above.
70
:Which of the following best describes M-Mode?
dEPTH OF REFLECTORS ALONG A SINGLE LINE OF SIGHT vs. time.
71
During the performance of a sonogram you would be most likely to encounter refraction in this view?
Curved interface. Refraction of the sound beam requires sound reflection from a curved interface
72
The conversion of an incident pressure wave to an electrical signal is the
Piezoelectric effect
73
While performing a sonographic exam, you increase both imaging depth and scan line density. These adjustments produce the following result
Reduced temporal resolution
74
You have chosen to enlarge an ultrasound image with a read magnification. Which of the following is NOT related to read magnification?
Preprocessing
75
If you increase the PRF and leave all other controls unchanged what will happen?
Frame rate will increase
76
When you adjust the pulse repetition frequency, you are changing
The number of pulses per second
77
Without interpolation, which of the following would best describe the resultant B-mode image?
A series of scan lines with blank data between the line
78
Transducer for cardiac imaging
Phased array
79
Spatial pulse length is equal to
The wavelength times the number of cycle in the pulse.
80
Bandwidth refers to
The range of frequencies in a pulse
81
What term refers to regions of decreased particle density in a sound beam?
Rarefaction
82
How is reflector depth determined with pulse-echo ultrasound
Echo arrival time
83
Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will
Decrease the wavelength
84
You have been requested to image a superficial mass and to adjust your equipment to optimize spatial resolution. Spatial resolution consists of
Lateral and axial
85
The regions of low pressure and density that are formed during sound propagation are termed
Rarefactions
86
If you wish to perform a sonogram with the largest possible field of view in both the near field and at depth, what type of array transducer would be most preferable?
Curved array
87
Increasing which of the following will result in improved axial resolution?
Frequency
88
Which of the following helps to improve the lATERAL RESOLUTION IN A b-MODE image?
Increased aperture
89
What transducer component is designed to control ringing of the piezoelectric element?
backing material
90
While preforming an obstetrical sonogram, you wish to increase the frame rate ot evaluate the fetal heart. What should you do?
Decrease the sector width
91
Which of the following describes sound propagation through a vacuum?
Sound can not travel through a vacuum.
92
Which adjustments increase the duty factor?
Increasing PRF
93
Which of the following frequencies is considered to be ultrasound?
2 MHz
94
What component of the ultrasound system convers the electric energy provided by the pulser into acoustic pulses transmitted into the patient?
Transducer
95
When you change the transmit frequency, which of the following is altered?
Number of cycles per second
96
What is the disadvantage of a water-path scanner
Bubbles in the fluid can inhibit sound transmission into the body.
97
When the sound beam is refracted during a sonographic examination, which of the following might you detect on the ultrasound image?
Lateral misregistration
98
Snell's law describes
The angle of sound transmission at an interface between media having different propagation speeds
The relative speed in two media is the angel of transmission as related to the incident beam angle
99
Requirements of magnetic field tracking for 3D reconstruction include
Minimization of electromagnetic interference
Transmitter must be in close proximity to the receiver
Ferrous metals must not be within the field
All of the above
100
What is the purpose of curving the transducer elements or applying a lens over the elements?
To provide focusing in the out of plane (elevational) direction
101
What is an advantage of single-crystal or pure-wave crystal transducers?
Wide bandwidth
102
The intensity transmission coefficient at the interface between two structures equals 1/100. What is the intensity reflection coefficient?
99/100
103
Which statement is NOT true regarding lateral resolution?
It remains constant throughout scanning depth.
104
Testicular
Electronic
105
Another name for axial resolution
Range resolution
106
You are imaging a structure containing two media having the same acoustic impedance. What will occur at the boundary of the two structures?
All of the sound will be transmitted.
107
What is a typical frame rate for B-mode real time imaging?
10-50 Hz
108
What is the main advantage you will have by choosing a transducer that produces a thin slice over the image plane?
Decreased volume averaging
109
Which of the following statements regarding the effect of frequency on Rayleigh scattering is TRUE?
Scattering intensity is proportional to frequency raised to the fourth power.
Rayleigh scatter=red blood cell
110
What is the purpose of subdicing?
To reduce grating lobes
111
Electronic noise is reduced in the ultrasound system by this method
Rejection
112
What is a side lobe
Sound beam emitted from the transducer that travels in a different directions from the main beam
113
For a single transducer to offer multiple frequency selections for scanning, it must have
wide bandwidth
114
If you increase pulse repetition frequency to a level too great for the depth of field, the result will be
Range ambiguity. (Misplaced axially)
115
What artifact will you see in the color Doppler image if you cannot increase the PRF to a level greater than 2 times that of the Doppler frequency shift?
Aliasing
116
Which prefix equals 10 to the third
Milli is -3
Micro is -6,
Mega is +6
Centi is -2
117
Which of the following describes diffuse reflection?
The reflected beam is scattered in various directions.
118
You are imaging a 3D dataset that has anisotropic resolution. What does this mean?
Unequal resolution is present between imaging planes.
| Isotropic resolution means the spatial resolution is equal.
119
Where is the point of maximum intensity in a sound beam?
Focal Point. The beam is the narrowest.
120
What can you improve by changing the gray-scale map?
Contrast resolution
121
The sound beam can be focused by all of the following except:
the matching layer
122
You may observe a mirror image articfact with whi8ch imaging mode
```
B-mode
Spectral Doppler
Color Doppler
Power Doppler
All of the above
```
123
During a sonographic exam, which one was most likely to have affected the frame rate?
Scan depth
124
The term signal to noise ration denotes
The relative amplitude of the signal compared to the amplitude of the noise.
125
What is an advantage of using a 3D/4D transducer with an automated sweep compared to a traditional transducer with a freehand sweep?
Measurement accuracy
126
An echo from which one of the following sound reflectors is most dependent on the angle of incidence?
Specular reflector
127
The shadow depicted in this image of a renal stone is primarily a result of the following sound-tissue interaction
Reflection
128
You are imaging with a 5 MHz linear array transducer. What sound parameter stays constant as the beam propagates through the tissue?
None of the above
129
When you increase the scanning depth, which of the following is automatically decreased by the system to avoid range ambiguity
PRF
130
A type of sonographic imaging that transmits two pulses of opposite phrase in rapid succession so they can be cancelled out upon reception is termed
Pulse inversion harmonics
131
Wavelength depends on
Frequency and propagation speed
132
What advantage will you obtain when using tissue harmonics operating mode?
Improved contrast resolution
133
A digital scan converter is another name for what system component?
Image memory
134
Wideband width improves
Axial resolution
135
Dynamic apodization is a method employed to
Reduces side lobes
136
Imaging frame rate decreases when you
Increase sector width
137
Acoustic impedance increases with which of the following
Increased tissue density
| Increased prop speed
138
What term descrivbes the rate at which the transmitter applies electronic voltage pulses to the transducer
PRF
139
What technique would be most likely to produce grating lobes in your image?
Beam steering
140
The technique of frame averaging during real-time acquisition is designed to
reduce random noise
141
What effect will you detect in the image if you increase the threshold control?
Decreased appearance of weak echo signals
142
What is the advantage of a water-path scanner?
Near-field reverberations are reduced.
143
You are performing a 3D sonogram and notice the volume rate is 8 Hz. What does this represent?
Number of volumes displayed per second.
144
Which describes constructive interference?
Sound waves are in phase an resulting amplitude is increased.
145
What type of focusing is performed by delay circuitry upon reception?
Dynamic receive focusing
146
What system control convers the numbers stored in memory to proportional voltages that control the brightness io a CRT monitor?
Digital to analog converter
147
The ultrasound in your lab has a transducer with a small footprint. This kind of transducer has the following disadvantage.
Resolution is degraded at large distances
148
Black image
A Lateral
B Elevation
C-Axial
149
Electronic focusing in the transmit mode is accomplished using
time delays to excite transducer elements
150
Which of the following is NOT a limitation of M-Mode scanning?
With M mode, motion lkateral to the transducer is not displayed but motion axial to the transducer is
151
Varying the excitation voltage to each element in the group used to form the ultrasound pulse is called
Apodization
152
What is the advantage of using Write zoom instead of Read zoom magnification?
Write zoom provides better spatial resolution than read zoom.
153
If the number of cycles in a pulse is increase but the wavelength remains the same, which of the following is true?
Pulse duration increases
154
Increasing the dynamic range setting affects the ultrasound image by
Decreasing image contrast
155
The matching layer between the piezoelectric element and the tissue is designed to
Reduce the acoustic impedance mismatch between the element and the tissue.
156
What can you do to improve contrast resolution in the ultrasound image?
Use a 2D or matrix array transducer
157
Choose two benefits of harmonic imaging
Grating lobe artifacts are reduced and lateral resolution is improved.
158
What type of resolution is determined by the number of pixels in the scan converter?
Spatial
159
With absorption, acoustic energy is converted to
Heat
160
Which one will not cause a redirection of part of the ultrasound energy?
Absorption
161
Which travels faster sound thru air or soft tissue?
Sound travels must slower through air than soft tissue. 330 m/s, 1540 m/s
162
What occurs when you image a structure with oblique incidence?
The angle of reflection will be oriented away from the transducer resulting in decreased visualization of the structure.
163
For pulsed ultrasound, which of the following factors determine the frequency of the sound wave?
Transmitter frequency.
164
You are using a transducer that produces a beam with a very wide slice thickness. Which of the following problems are you most likely to encounter as a result?
Partial volume artifact
165
In order to focus a sound beam relatively far away from the transducer, it is advantageous to
Increase the diameter of the element
166
What can you do to improve the temporal resolution while scanning?>
Decrease the acoustic scan line density
167
Preprocessing functions are
a function that is performed before the echo data are stored in memory
168
When you image a structure that is a specular reflector, the strength depends on the following two factors
Difference in acoustic impedance
| Angle of incidence
169
What two conditions must be present to cause refraction of a sound wave
Oblique incidence and different media propagation speeds
170
Doppler pulses used for diagnostic purposes are typically ____ cycles long.
5-30
171
If you are using a transducer with poor elevation resolution, which of the following problems are you most likely to encounter?
Inability to clearly demonstrate small cystic structures
172
Which of the following minimizes the degree to which beam width varies with depth?
Dynamic aperture
173
As a general observation about media in diagnostic sonography, sound propagates faster I materials with greater
Stiffness
174
Which of the following would increase the spatial pulse length
Increased number of cycles per pulse
175
What is the relationship of frequency to absorption
If frequency is doubled then absorption is doubled.
176
In sound wave propagation, a region of elevated pressure is termed
Compression
177
What transducer component reduces reflection at the transducer/skin surface?
Matching layer
178
The number of images displayed per second in real time is termed
frame rate
179
You are using a linear array transducer to evaluate the thyroid gland. For standard B-mode imaging, this transducer most likely produces pulses of how many cycles?
One to three
180
You have increased the output power by 10 dB. The signal intensity has
increased by a factor of 10.
181
In this image of an artery there is a calcification with a dark vertical band extending beyond it. Which explanation best describes the etiology of the dark band?
Reduction in signal amplitude in tissue distal to a highly attenuating or reflecting object.
182
You are scanning a large mass that is primarily fat. Which of the following are you most likely to encounter?
Axial misregistration of objects distal to the mass on the screen due to the slower propagation speed through fat.
183
Which of the following artifacts commonly results in echoes filling in the lumen of small vessels
Partial volume
184
Which of the following best describes the f-number?
Focal length divided by the aperture
185
With a standard one-dimensional linear array transducer, what type of resolution is affetcted most by electronic focusing and dynamic aperture?
Lateral resolution
186
Pulse repetition period is the inverse of
PRF
| Pulse repetition period is the time between pulses.
187
What effect will you see in the image if you increase the reject level?
Decreased low level echoes
188
Ultrasound propagation velocity depends on
density and compressibility
189
What interaction of ultrasound and tissue is primarily responsible for imaging for the internal structure of organs
Scattering
190
Disadvantage of a tightly curved array transducer..
Lateral resolution degrades with depth
191
Axial resolution is determined by
Pulse duration
192
For a linear array transducer consisting of a single row of elements, what method is most used to focus the beam in the elevational direction?
Mechanical focusing
193
Which of the following describes an analog signal
Continuous variation of the signal is possible
194
The transducer you are using transmits wide-bandwidth pulses whose frequency content is 2-5 MHz. Which of the following most correctly describes the reflected echo after they have traversed the tissue.
The echo signals will be shifted down in frequency due to the increased attenuation of higher frequencies.
195
What represents the best measure of resolution for modern day ultrasound scanners?
axial
196
Which of the following artifacts may result in both an axial and lateral displacement of a reflector on the ultrasound image?
Multipath artifact
197
With A-mode, the strength of the echo signal is represented by
The height of the spike
198
What type of transducer has the same measurement for elevational and lateral resolution
Annular array
199
You have obtained an ultrasound image that demonstrates refraction of the sound beam. This artifact may be manifested as
Lateral displacement of the displayed position of a reflector
200
What happens when pressure is applied to a piezoelectcal crystal?
It emits an electrical signal
201
Which of the following increases as frequency increases
All of the above
202
Acoustic impedance
Equals density times the propagation speed
203
What is the purpose of the preamplification of the incoming signal that occurs in the transducer assembly?
To increase echo voltages before noise is induced through the cable
204
The ability to distinguish between adjacent structures that produce echoes of similar amplitude is termed
contrast resolution
205
If the number of cycles in the transmitted pulsed wave is increased
Axial resolution is degraded
206
Which of the following helps to improve axial resolution in a B-mode image
Increase bandwidth
207
Diagnostic ultrasound is limited in its diagnostic application to the adult brain because
The great acoustic impedance mismatch between the cranium and soft tissue causes most of the sound to be reflected at that interface
208
Interference patterns of reflected waves causes
Acoustic speckle
209
system performance order
Pulser, beam former, receiver, memory, display
210
A-mode lines of sight=
1
211
What benefits would you obtain by choosing a transducer having a large diameter c9mpared to one having a small diameter
It can focus at greater depths.
212
Electronic steering is most commonly applied to which of the following real time transducers
Phased array
213
To alter dynamic range, which control would you use
Compression
214
Which of the following helps to improve the elevation resolution in B-mode image.
Focusing with an acoustic lens
215
What control should you adjust to modify the image if the attenuation coefficient of the tissue is very high
Compensation
216
When you adjust the TGC, what component of the ultrasound system implements the changes?
The receiver
217
When an electrical signal is applied to a piezoelectric element, what happens
It expands and contracts
218
What defines the best axial resolution that can be obtained with a given transducer?
SPL/ 2
219
What is the disadvantage of using multiple transmit focal zones
Decreased temporal resolution
220
The algebraic summation of waves leading to patterns of minima and maxima is called
Interference
221
You are using a 45 MHz , 40 mm linear array transducer to image a structure. What is the width of the image
40 mm
222
Artifact associated with resonance of a gas bubble
Ring down
223
For soft tissue, one of the factors responsible for determining acoustic impedance is
Density
224
The maximum cyclical change in a quantity is known as
Amplitude
225
Purpose of radiofrequency shield around the crystal and backing material of the ultrasound probe
It reduces electromagnetic interference
226
Another term for nonspecular reflection is
Scattering
227
Dynamic receive focusing uses
Time delays
228
What is required for sound reflection at the interface of two structures
A difference in the acoustic impedance of the media
229
What does not affect impedance
Frequency
230
What scanning mode does not rely on the principle of echo ranging to determine interface location
Transmission
231
A standard for handling and transferring images and medical information between computers
DICOM
232
Which phenomenon is associated with a pattern produced by a sound beam after passing through a small aperture
Diffraction
233
You have decreased the acoustic power by -3 dB. Which of the following most accurately describes this adjustment?
The intensity has been halved.
234
Relationship between Doppler and B-mode
Doppler frequency is usually lower than for imaging.
235
If you choose a lower frequency traqnsducer to image a highly attenuating structure, what tradeoff are you making?
Decreased spatial resolution for improved penetration.
236
Which is the best choice to help you demonstrate tissue boundaries that are not perpendicular to the sound beam
Spatial componding
237
What type of transducer could you choose to produce a beam that is symmetrical about the beam axis.
Annular array
238
Shadowing at the lateral edges o a structure. Is caused by
Different media propagation speeds
239
Phantom is evaluated by what type of resolution
Elevational
240
Purpose of applying multiple matching layers to the transducer face
Multiple matching layers result in increased transducer bandwidth
241
A-mode display contents of cyst will appear as
an area with no spikes
242
What artifact is related to Beam attenuation
enhancement
243
A commonly used material in modern transducer elements is
Lead zirconate titanate
244
Which of the following is not associated with a Low-Q transducer
Long pulse length
